Fully 30% of U.S. adults -- or 40.6 million workers -- sleep six or fewer hours a day, a new CDC report shows.

The National Sleep Foundation recommends we get seven to nine hours of sleep each day. Most at risk, according to the report, are people who work the night shift, especially those in the transportation, warehouse, and health care industries.

And sleep deprivation has consequences. "If a person doesn't get the recommended amount of sleep, they are at increased risk of injuries that could affect them or the general public if they are a commercial driver," says researcher Sara Luckhaupt, MD, MPH. She is a medical officer in the division of surveillance, hazard evaluations, and field studies at the National Institute for Occupational Safety and Health in Washington, D.C.

Illuminating Luckhaupt's point: Drowsy drivers play a role in up to 20% of car crashes.

According to the new report, 44% of people who worked the night shift were short-sleepers, compared with 28.8% of those who worked during the day. People aged 30 to 44 made up the age group most likely to be sleep deprived.

Others who are not getting enough sleep include people who hold down more than one job, widows, divorcees, or recently separated partners. The findings are based on data from the 2010 National Health Interview Survey. They appear in the April 27 issue of the CDC's Morbidity and Mortality Weekly Report.

Sleep Tips for Employers and Employees

Getting more sleep may be easier said the done in today's hyper-competitive, no-downtime society.

Still, employers can, and should, take steps to make sure that workers are getting the appropriate amount of sleep. This may mean tweaking night shift schedules and placing limits on how many nights a person can work in a row, Luckhaupt says.

Employee wellness initiatives should also include education about a healthy sleep routine.

This mean encouraging workers to:

Go to bed at the same time each day or night.

Create a relaxing bedroom environment that is conducive to sleep.

Avoid reading or watching TV in bed.

Avoid large meals before bed.

Turn off their mobile phone or PDA before sleep.

Are You Sleep Deprived?

Sleep deprivation is serious, says Mark W. Mahowald, MD. He is a neurologist and director of the Minnesota Regional Sleep Disorders Center in Rochester. "One of the biggest myths is that sleep is negotiable and something that we can get by with less and less and less of."

Pulling an all-nighter should not give you bragging rights. "Any degree of sleep deprivation impairs performance or mood," he says. "Our society has got to learn to respect sleep as biologically imperative. Getting a good night's sleep is as important as exercising regularly and eating a good diet."

How do you know if you are not getting enough ZZZs? If you need an alarm clock to get up, you are sleep-deprived, he says.

"If you hit the snooze button more than twice you are probably sleep-deprived," says sleep expert Michael J. Breus, PhD. Another clue is if you fall asleep in less than 10 minutes.

He is not surprised by the new study's finding that night shift workers and people in transportation, health care, and the warehousing business are the hardest hit.

But another group of short-sleepers is stay-at-home parents. "I would love to see moms in their first year with kids and compare their sleep to that of night shift workers. I bet new moms would be worse, and they are the ones driving 4,000-pound SUVs," he says.